This invention relates to an adjustable brush. More particularly, this invention relates to a circular brush, the effective working diameter of which may be adjusted. In particular, this invention relates to an adjustable brush specifically adapted for cleaning the points of various sizes of distributor caps.
The distributor of a typical internal combustion engine comprises a cup-shaped member called a distributor cap which has in its interior a plurality of electrical contacts called points. Not infrequently, the electrical contacts or points will become fouled with corrosion products or foreign material. This may interfere with the proper transmission of an electrical spark to the cylinders to ignite the fuel/air mixture thereby resulting in poor operation of the engine. Thus, it becomes necessary at intervals to clean the points in the interior of a distributor cap. Most commonly, such a cleaning operation is effected by scraping the points with an instrument such as the blade of a pocket knife. Such a procedure is inefficient both from the standpoint of the time required and from the standpoint of the efficacy of the result.
Specialized tools have been proposed for cleaning distributor contacts. For Example, Ross, U.S. Pat. No. 1,188,837 discloses a device for grinding the commutators of old-fashioned distributors with a grinding wheel or disk. Similarly, Morris, U.S. Pat. No. 1,570,166 discloses a grinding tool comprising a longitudinally split wooden cylinder with a band of emery cloth around one end. The diameter of the wooden cylinder may be slightly adjusted by forcing a tapered body into a central bore in the cylinder. Such devices are manifestly unsuitable for cleaning the points of modern distributors.
Merchant, U.S. Pat. No. 2,476,156 discloses a circular brush for cleaning the terminals of a distributor. The effective working diameter of this brush is fixed so that it is only useful for a single size of distributor cap. Since distributor caps come in many different sizes, a mechanic would need an impracticably large number of different size brushes in order to have the proper size brush for cleaning each distributor cap.
Brushes with adjustable effective working diameters are known. An adjustable brush for cleaning tobacco pipes is disclosed in Pfabe, U.S. Pat. No. 1,510,499. Another adjustable brush for cleaning receptacles such as tin cans is disclosed in Rude, U.S. Pat. No. 1,308,195. Such adjustable brush designs are not suitable for cleaning the points of a distributor cap.
There remains a need for a single tool for effectively cleaning the points on the inside of a distributor cap which is readily adjustable so as to be suitable for cleaning various sizes of distributor caps.